Hi Yes you just add a domain.com zone to your internal DNS and the create a A record for your CAS's internal internal IP. The only additional thing is that you need to add is matching A records to your internal DNS domain.com zone for all the records that currently exist in your public DNS e.g. your www.domain.com with it's current public IP. This is just so that your internal clients can still resolve these names. Cheers, Steve

Hello, For the internal side: You can add A record for mail.domain.com and point to the your CAS array. For the external side: You can add A record point for mail.domain.com and point to your firewall server. On the firewall, map the public ip with 443 to the internal ip for CAS array. When user try to access mail.domain.com from internet, it also will point to the CAS array. Thanks, EvanEvan Liu TechNet Community Support

Having split DNS is not mandatory for a 2010 deployment, it will make your namespaces a bit easier. It is always a nightmare to manage two zones for your internet use. If you go with split DNS, anytime a record is changes in the public DNS, you will have to make that change internally as well. If you have too many records in your public DNS, going down the split DNS route will create more issues later on.Rajith Enchiparambil | http://www.howexchangeworks.com |

We have an existing Exchange 2003 system and are single site, about 500 users. I am planning deployment for EX2010 and have been reading as much as I can get my hands on, with great confusion about split DNS. We have two internal Windows 2008 DNS servers. Our internet service provider hosts our external/Internet DNS records. They do not share zone information and our internal DNS servers are not accessible from the outside. Do I just need to add a record to our internal DNS servers for mail.domain.com that points to the internal address of our CAS array and add a record to our hosted external DNS that points to the external address (to be NAT'd to the internal address through our firewall) for our CAS array? That seems ridiculously straight-forward, so I think I must be missing something. Thank you in advance.

Hi Yes you just add a domain.com zone to your internal DNS and the create a A record for your CAS's internal internal IP. The only additional thing is that you need to add is matching A records to your internal DNS domain.com zone for all the records that currently exist in your public DNS e.g. your www.domain.com with it's current public IP. This is just so that your internal clients can still resolve these names. Cheers, Steve